Without limiting the scope of the invention, its background is described in connection with belt driven motorcycle sprockets, as an example.
Heretofore, in this field, belt driven sprockets have been used to drive the rear wheel of a motorcycle. Typically, these sprockets have a plurality of circumferentially spaced teeth that are axially aligned and may receive a positive drive belt therein such that the teeth of the positive drive belt move into and out of engagement with the teeth of the sprocket to transfer a driving force to the sprocket. The positive drive belt has teeth that are generally round in cross section and are able to mesh with a sprocket having conjugate mating teeth.
The sprocket distributes a driving load to the belt along the entire driving surface of the belt teeth to effect a stress distribution. Thus, these round belt teeth are suitable to receive high sprocket loading in high torque drives. Also, the round belt teeth have sufficient depth to exhibit anti-ratcheting qualities at high tension ratios such as that which may be encountered in a fixed two-point drive which may become loosened through belt tension decay.
It has been found, however, that when a conventional sprocket is used on a motorcycle, the size of the rear tire is limited by the interference between the rear tire and the drive belt. In fact, the use of a super-wide rear tire is one of the most desirable looks on a motorcycle and, in particular, on a custom Harley. In addition, it has been found that the use of a super-wide rear tire provides a softer ride, better feel for the road, and more stability.
In order to install a super-wide tire on a motorcycle, many people have offset their motor, transmission and rear wheel. Other people have changed the frames and/or swingarms of a motorcycle in order to accommodate such a super-wide rear tire. All of these modifications, however, result in two undesirable and detrimental outcomes. Specifically, these modifications can be extremely expensive and these modifications usually result in a motorcycle that pulls to one side when it is driven in a straight line. In addition to these problems, modifications to original equipment may result in a warranty on the motorcycle becoming void.
More recently, an aftermarket kit has been marketed which may be coupled with an existing motorcycle sprocket to allow for the use of a super-wide rear tire without the necessity of offsetting the motor or the transmission and without changing frames or swingarms. This kit, however, is expensive and it requires the use of shims to offset the sprocket relative to the rear tire.
Therefore, a need has arisen for a belt driven sprocket for use in driving the rear wheel of a motorcycle that allows for the use of a super-wide tire without requiring the offset of the motor, the transmission, or the existing sprocket and without requiring the need to change frames or swingarms.